Study of heat transformation systems for cooling, heat pumps and desalination

• Main Author: Lee, Jia Wei
• Other Authors: Anutosh Chakraborty
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Science::Physics::Heat and thermodynamics; Engineering::Mathematics and analysis::Simulations; Science::Mathematics::Applied mathematics::Simulation and modeling; Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/150705
• Institution: Nanyang Technological University

This report studies about UiO66 (Zr) and its functionalised group (-OH, -N, and -NH2) with H2O as compatible working adsorbate-adsorbent pairs that is being deployed in the adsorption assisted heat transformation (AHT) system for cooling, heating, and desalination of water. This report consists of literature reviews on AHT system and metal-organic frameworks, thermodynamics modelling, and detailed simulation results. Employing experimentally confirmed isotherms and kinetics data of MOFs – water systems, a simulation study for each component of AHT system is conducted to predict the overall performances of AHT system in terms of specific cooling power, coefficient of performance (for both heating and cooling), specific heating power and specific daily water production. These performance parameters are calculated for various operating conditions such as hot water (heat source) inlet temperature, chilled-water inlet temperature, switching and cycle time. The isotherms and kinetics data are fitted with modified Langmuir equation. The thermodynamic modelling is based on simple mass and energy balance approaches. Hence, a lumped approach is considered for simplicity. The parent UiO66 (Zr) MOFs are not found suitable for cooling applications due to its longer hydrophobic length in the low pressure region with water adsorption. Therefore, MOF-linker-functionalisation strategy is considered. Hence, pyridine, amino, and hydroxyl functional groups based UiO-66 (Zr) MOFs + water assisted AHT are simulated. It is found that -N MOF has improved SDWP of 28 m3 per ton of MOF per day as compared to parent MOF which is only 18 m3 per ton of MOF per day. -OH MOF has SCP of 0.6 kW/kg whereas parent MOF only has 0.04 kW/kg at 80 °C and 500 s half cycle time. -OH MOF has SHP of 1.1 kW/kg whereas parent MOF only has 1 kW/kg at 80 °C and 100 s half cycle time. These results confirm that functionalised UiO-66 (Zr) MOFs are competent candidates for adsorption cooling, heat pump and desalination applications.